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參數(shù)資料
| 型號： | L6725ATR |
| 廠商： | STMICROELECTRONICS |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 20 A SWITCHING CONTROLLER, 500 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封裝： | SOP-16 |
| 文件頁數(shù)： | 9/34頁 |
| 文件大?。?/td> | 962K |
| 代理商： | L6725ATR |
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L6725 - L6725A
Device description
17/32
5.12
Bootstrap anti-discharging system
This built-in system avoids that the voltage across the bootstrap capacitor becomes less than
3.3V. An internal comparator senses the voltage across the external bootstrap capacitor
keeping it charged, eventually turning-on the low-side MOSFET for approximately 200ns. If the
bootstrap capacitor is not enough charged the high-side MOSFET cannot be effectively turned-
on and it will present a higher RDSON. In some cases the OCP can be also triggered. The
bootstrap capacitor can be discharged during the soft-start in case of very long soft-start time
and light loads. It's also possible to mention one application condition during which the
bootstrap capacitor can be discharged:
5.12.1 Fan's power supply
In many applications the FAN is a DC MOTOR driven by a voltage-mode DC/DC converter.
Often only the speed of the MOTOR is controlled by varying the voltage applied to the input
terminal and there's no control on the torque because the current is not directly controlled. In
order to vary the MOTOR speed the output voltage of the converter must be varied. The L6725
has a dedicated pin called EAREF (see the related section) that allows providing an external
reference to the non-inverting input of the error-amplifier.
In these applications the duty cycle depends on the MOTOR's speed and sometimes 100% has
to be set in order to go at the maximum speed. Unfortunately in these conditions the bootstrap
capacitor can not be recharged and the system cannot work properly. Some PWM controller
limits the maximum duty-cycle to 80-90% in order to keep the bootstrap cap charged but this
make worse the performance during the load transient. Thanks to the "bootstrap anti-
discharging system" the L6732 can work at 100% without any problem. The following picture
shows the device behaviour when input voltage is 5V and 100% is set by the external
reference.
Figure 12. 100% duty cycle operation
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| L6727TR | 1.5 A SWITCHING CONTROLLER, 350 kHz SWITCHING FREQ-MAX, PDSO8 |
| L6727 | 1.5 A SWITCHING CONTROLLER, 350 kHz SWITCHING FREQ-MAX, PDSO8 |
| L6728AHTR | SWITCHING CONTROLLER, PDSO10 |
| L6730DTR | 20 A SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PDSO20 |
| L6730D | 20 A SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PDSO20 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| L6725TR | 功能描述:電壓模式 PWM 控制器 Adjustable Step Down Controller RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
| L6726 | 制造商:UTC-IC 制造商全稱:UTC-IC 功能描述:UNIVERSAL SPEECH CIRCUIT |
| L6726_08 | 制造商:UTC-IC 制造商全稱:UTC-IC 功能描述:UNIVERSAL SPEECH CIRCUIT |
| L6726_12 | 制造商:UTC-IC 制造商全稱:UTC-IC 功能描述:UNIVERSAL SPEECH CIRCUIT |
| L6726A | 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 Sngl phase PWM controller RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開關(guān)頻率:1 MHz 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
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